Unfilled audio and video tape cassettes essentially comprise a shell made of plastic material, rotatably housing first and second winding hubs, around which a leader tape of predetermined length is wound. The leader tape extends along an access opening formed in the shell and is optionally protected by an openable lid.
In industrial processes for making these cassettes, automatic machines are currently used in which magnetic tape is fed from a supply reel and guided to a loading station in which the cassettes being processed are individually engaged. At the loading station, the cassettes are loaded with a predetermined amount of magnetic tape and then discharged onto a conveyor or other means to move them away from the loading machine.
Prior to being loaded with tape, cassettes reaching the loading station are acted upon by extractor means which takes the leader out via the cassette access opening to submit the leader to the action of a cutting and splicing unit.
The cutting and splicing unit is generally arranged such that it engages the leader and magnetic tape on first, second and third supporting surfaces formed in two or more blocks. In greater detail, the first supporting surface is formed on a first block which is fixed relative to a front panel of the loading machine. The second and third supporting surfaces, formed on one or two movable blocks, can be individually and selectively moved close to the first supporting surface and aligned in coplanar relation therewith. Typically, when the leader is extracted from the cassette, the first and second supporting surfaces are aligned in coplanar relation with each other to receive the leader thereon. The leader is generally retained on the support surfaces by suction produced through holes in the surfaces.
A movable blade then cuts the leader into a leading portion and a trailing portion which is connected to the first and second winding hubs, respectively.
At this point, the movable block or blocks are moved to cause the first supporting surface carrying the leading portion of the cut leader to be aligned in coplanar relation with the third supporting surface holding the magnetic tape end from the supply reel which is mounted on the loading machine. The ends of the magnetic tape and leading portion of the leader, aligned end-to-end, are spliced together with a piece of adhesive tape carried by an applicator member which has received the tape from a supply unit. The supply unit pulls the adhesive tape from a feed roll, moves it forward and cuts it into pieces of predetermined length in conjunction with each work cycle of the applicator member.
When splicing has been completed, the first winding hub is driven in rotation to cause the winding of a predetermined amount of magnetic tape into the cassette. When the winding is complete, the magnetic tape extending on the first and third supporting surfaces is cut by the movable blade. The positioning between the third and second supporting surfaces is then changed so that the trailing portion of the leader is moved into alignment with the end of the cut magnetic tape located on the first supporting surface and then spliced to the end of the magnetic tape by application of another piece of adhesive tape carried by the applicator member.
The trailing portion of the leader and end portion of the adhesive tape remaining outside the cassette shell are wound into the cassette and the cassette is ejected from the loading station.
Several different types of cutting and splicing units are available. While these units are similar in manufacturing and operating concept, they have different structural and practical features that are selected depending upon the type of cassettes being processed and the length of the leader therein.
"Philips type" audio cassettes have a relatively long leader. When these cassettes are to be processed, the blocks carrying the leader and the magnetic tape supporting surfaces are generally spaced apart sideways relative to the loading station. Typically, the second and third supporting surfaces are formed on a single movable block disposed close to the fixed block and movable perpendicularly to the front panel of the machine in order to selectively align the second or third supporting surfaces with the first supporting surface.
Video tapes of the "VHS" and "BETA" formats have a shorter leader than Philips cassettes. In machines designed to load these cassettes the blocks carrying the supporting surfaces usually located very close to the front of the access opening of the cassette when the cassette is in place in the loading station. In addition, the blocks are simultaneously movable close to and away from the front panel of the machine so that, on splicing, the supporting surfaces carrying the tape and leader to be spliced are disposed in vertical alignment relation with the applicator member associated with the adhesive tape supply unit, the latter being disposed behind the cassette being processed.
Audio and/or video cassettes, of the "VIDEO 8" and "DAT" format have a leader which is very short. In fact, the length of the leader is so reduced that it is impossible to move the blocks sideways in order to align them with the applicator member, as described with reference to "VHS" cassettes.
A cutting and splicing unit envisaged to work under the above conditions is disclosed in U.S. Pat. No. 4,974,785. In this cutting and splicing unit the second and third supporting surfaces are formed on a second and third blocks respectively, that are movable independently of each other close to and apart from the first block, fastened to the front panel very close to the access opening of the cassette being processed. In greater detail, the second block is movable in the longitudinal extension direction of the leader between one position, in which it is close to the first block and a second position in which it is spaced apart from the first block. Located in the gap defined between the first block and second block and spaced apart from the first block is a third block which is movable in a direction perpendicular to the extension of the leader extracted from the cassette. The cutting member moves through an opening of the front panel in a direction at right angles to the longitudinal extension of the leader.
The adhesive tape supply unit is located behind the front panel of the machine with the applicator member reaching the junction area between the blocks through an opening formed in the machine's front panel.
While, this cutting and splicing unit is capable of operating with very short leaders, it does have several drawbacks. For example, the magnetic tape which comes from the reel must be threaded through a rather tortuous path between several idler rollers. In fact, after the tape passes beyond the control and counter unit it passes over a first idler roller and then, before reaching the third supporting surface, it must make a complete turn around the third block. This is very undesirable, in that each element which the tape must pass over represents a possible damaging factor for the tape when the cassette is being loaded. The possibility of tape damage increases when the tape is run at high speed over the elements. This speed can reach and exceed forty meters per second.
The positioning of the adhesive tape supply unit behind the front panel of the machine is also a drawback when the adhesive tape roll must be replaced. These problems are very important because of the high degree of automation presently required by tape loading operations.
In addition, the time necessary to enable the cutting member and applicator member to operate from their locations behind the front panel of the machine adversely affects productivity.
Another cutting and splicing unit is disclosed in European Patent No. 0 210 844 (corresponding to U.S. Pat. No. 4,911,774). This device comprises a fixed block having a first supporting surface on which the magnetic tape end is held. A second supporting surface holds the leading portion of the leader transversely cut by a blade. The trailing portion of the leader is kept in engagement with an extractor element that, after reaching the same level as the supporting surface to lay the leader thereon for it to be cut, goes back to the cassette access opening. This moves the trailing portion away from the block to enable the magnetic tape to be spliced to the leading portion. At the end of the tape winding operation, the extractor element puts the trailing portion on the block again to enable it to be spliced to the end portion of the tape, previously cut by the blade.
This splicing unit also has similar drawbacks. The magnetic tape slides on the block during the winding step. Further, the cutting and splicing operations are carried out individually at subsequent times, while the adhesive tape supply unit is again located behind the front panel of the machine.